How to disable Command-W Everywhere?

BetterTouchTool is a free utility which can disable keyboard shortcuts: http://www.boastr.de/

To disable command-w globally:

1. Install BetterTouchTool
2. Click on the BetterTouchTool menubar item and choose "Preferences"
3. Click "Gestures"
4. Click "Keyboard"
5. Click "Global"
6. Click "Add New Shortcut"
7. Click "Keyboard Shortcut"
8. Type the shortcut you want to disable (for example, command-w)
9. Set Trigger Predefined Action to "No Action" (which is the default)